scholarly journals Bistatic ISAR Sparse Imaging Method for High-Speed Moving Target Based on Dechirping Processing

2019 ◽  
Vol 2019 ◽  
pp. 1-15
Author(s):  
Chuangzhan Zeng ◽  
Weigang Zhu ◽  
Xin Jia
Keyword(s):  
High Speed ◽  
Distortion Correction ◽  
Geometric Distortion ◽  
Posteriori Probability ◽  
Imaging Method ◽  
Moving Target ◽  
Geometric Correction ◽  
Distortion Factor ◽  
A Posteriori Probability ◽  
Isar Imaging

Bistatic inverse synthetic aperture radar (ISAR) can increase the probability of tracking the high-speed target and provide more angle information than monostatic ISAR. However, bistatic ISAR suffers from a serious defocusing problem, resulting from the high-speed motion. Furthermore, the inherent geometry distortion and calibration problems make bistatic ISAR (B-ISAR) imaging more complex. In response to these problems, we propose a bistatic ISAR imaging method for high-speed moving target with geometric distortion correction and calibration based on dechirping processing. At first, based on the motion decomposition idea, the B-ISAR echo model of the high-speed moving target is established. Then, by analyzing the imaging mechanism of the Range-Doppler algorithm (RDA), we eliminate the phase items influencing the imaging quality with speed compensation and Doppler compensation. After that, the analytic formula of the geometric distortion factor and calibration factor are deduced, which helps transform the geometric correction and calibration problem into a parameter estimation problem. Finally, with the sparsity of the scattering points, the required parameters are solved using the expectation maximization (EM) algorithm based on the maximum a posteriori probability criterion. With the estimated parameters, a clear B-ISAR image of a high-speed moving target with geometric correction and calibration is obtained. The simulations show that the proposed method has a better resolution and simultaneously attains geometric correction and calibration of the image.

scholarly journals Three-Dimensional ISAR Imaging Method for High-Speed Targets in Short-Range Using Impulse Radar Based on SIMO Array

Sensors ◽  
2016 ◽  
Vol 16 (3) ◽  
pp. 364 ◽  
Author(s):  
Xinpeng Zhou ◽  
Guohua Wei ◽  
Siliang Wu ◽  
Dawei Wang
Keyword(s):  
High Speed ◽  
Short Range ◽  
Three Dimensional ◽  
Imaging Method ◽  
Isar Imaging

scholarly journals An area efficient and high throughput implementation of layered min-sum iterative construction a posteriori probability LDPC decoder

PLoS ONE ◽  
2021 ◽  
Vol 16 (3) ◽  
pp. e0249269
Author(s):  
Hasnain Raza ◽  
Syed Azhar Ali Zaidi ◽  
Aamir Rashid ◽  
Shafiq Haider
Keyword(s):  
High Throughput ◽  
High Speed ◽  
Ldpc Code ◽  
Error Correcting Codes ◽  
Posteriori Probability ◽  
A Posteriori ◽  
Error Performance ◽  
A Posteriori Probability ◽  
Iterative Construction ◽  
Area Efficient

Area efficient and high speed forward error correcting codes decoder are the demand of many high speed next generation communication standards. This paper explores a low complexity decoding algorithm of low density parity check codes, called the min-sum iterative construction a posteriori probability (MS-IC-APP), for this purpose. We performed the error performance analysis of MS-IC-APP for a (648,1296) regular QC-LDPC code and proposed an area and throughput optimized hardware implementation of MS-IC-APP. We proposed to use the layered scheduling of MS-IC-APP and performed other optimizations at architecture level to reduce the area and to increase the throughput of the decoder. Synthesis results show 6.95 times less area and 4 times high throughput as compared to the standard min-sum decoder. The area and throughput are also comparable to the improved variants of hard-decision bit-flipping (BF) decoders, whereas, the simulation results show a coding gain of 2.5 over the best implementation of BF decoder in terms of error performance.

Micro-Motion ISAR Imaging Method Based on MP Sparse Decomposition for Fast Moving Target

2013 ◽  
Vol 760-762 ◽  
pp. 1482-1485 ◽  
Author(s):  
Jian Gong ◽  
Teng Lei ◽  
Zhi Long Li ◽  
Chuang Li
Keyword(s):  
Azimuth Angle ◽  
Imaging Method ◽  
Moving Target ◽  
Cross Term ◽  
Imaging Algorithm ◽  
Sparse Decomposition ◽  
Range Resolution ◽  
Range Cell ◽  
Isar Imaging ◽  
Micro Motion

In this paper, a new micro-motion ISAR imaging algorithm is proposed, which achieve high cross range resolution by using the changes of azimuth angle caused by micro-motion. Before Wigner-Ville transformation to eliminate the cross-term interference, the echoes of the same range cell are decomposed. Comparing to traditional the Wigner-Ville imaging algorithm and Range-Doppler algorithm, this new algorithm in this paper has better imaging precision and no cross-term interference is existed. At last, the effectivity of the proposed algorithm is demonstrated by the simulated results.

Accurate Imaging Method for Moving Target with Arbitrary Shape for Multi-Static UWB Radar

2013 ◽  
Vol E96.B (7) ◽  
pp. 2014-2023 ◽  
Author(s):  
Ryo YAMAGUCHI ◽  
Shouhei KIDERA ◽  
Tetsuo KIRIMOTO
Keyword(s):  
Arbitrary Shape ◽  
Imaging Method ◽  
Moving Target ◽  
Uwb Radar ◽  
Accurate Imaging

scholarly journals High-speed volumetric two-photon fluorescence imaging of neurovascular dynamics

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Jiang Lan Fan ◽  
Jose A. Rivera ◽  
Wei Sun ◽  
John Peterson ◽  
Henry Haeberle ◽  
...  
Keyword(s):  
Blood Flow ◽  
High Speed ◽  
Laser Scanning ◽  
Three Dimensional ◽  
Laser Scanning Microscopy ◽  
Fluorescence Signal ◽  
Imaging Method ◽  
Spatiotemporal Resolution ◽  
Two Photon

AbstractUnderstanding the structure and function of vasculature in the brain requires us to monitor distributed hemodynamics at high spatial and temporal resolution in three-dimensional (3D) volumes in vivo. Currently, a volumetric vasculature imaging method with sub-capillary spatial resolution and blood flow-resolving speed is lacking. Here, using two-photon laser scanning microscopy (TPLSM) with an axially extended Bessel focus, we capture volumetric hemodynamics in the awake mouse brain at a spatiotemporal resolution sufficient for measuring capillary size and blood flow. With Bessel TPLSM, the fluorescence signal of a vessel becomes proportional to its size, which enables convenient intensity-based analysis of vessel dilation and constriction dynamics in large volumes. We observe entrainment of vasodilation and vasoconstriction with pupil diameter and measure 3D blood flow at 99 volumes/second. Demonstrating high-throughput monitoring of hemodynamics in the awake brain, we expect Bessel TPLSM to make broad impacts on neurovasculature research.

scholarly journals A Tree Ring Measurement Method Based on Error Correction in Digital Image of Stem Analysis Disk

Forests ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 464
Author(s):  
Wenjie Zhang ◽  
Tianzhong Zhao ◽  
Xiaohui Su ◽  
Baoguo Wu ◽  
Zhiqiang Min ◽  
...  
Keyword(s):  
Error Correction ◽  
Tree Ring ◽  
Tree Rings ◽  
Digital Image ◽  
Regression Equation ◽  
Distortion Correction ◽  
Geometric Distortion ◽  
Stem Analysis ◽  
Correction Model ◽  
Ring Radius

Stem analysis is an essential aspect in forestry investigation and forest management, as it is a primary method to study the growth law of trees. Stem analysis requires measuring the width and number of tree rings to ensure the accurate measurement, expand applicable tree species, and reduce operation cost. This study explores the use of Open Source Computer Vision Library (Open CV) to measure the ring radius of analytic wood disk digital images, and establish a regression equation of ring radius based on image geometric distortion correction. Here, a digital camera was used to photograph the stem disks’ tree rings to obtain digital images. The images were preprocessed with Open CV to measure the disk’s annual ring radius. The error correction model based on the least-square polynomial fitting method was established for digital image geometric distortion correction. Finally, a regression equation for tree ring radius based on the error correction model was established. Through the above steps, click the intersection point between the radius line and each ring to get the pixel distance from the ring to the pith, then the size of ring radius can be calculated by the regression equation of ring radius. The study’s method was used to measure the digital image of the Chinese fir stem disk and compare it with the actual value. The results showed that the maximum error of this method was 0.15 cm, the average error was 0.04 cm, and the average detection accuracy reached 99.34%, which met the requirements for measuring the tree ring radius by stem disk analysis. This method is simple, accurate, and suitable for coniferous and broad-leaved species, which allows researchers to analyze tree ring radius measurement, and is of great significance for analyzing the tree growth process.

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